Potassium Permanganate → 2,4-Dibromo-1,3-thiazole-5-carboxylic acid

Participants

Reaction Steps

Solid potassium permanganate (2.19 g, 13.85 mmol) was added portionwise to a hot suspension of 2,4-dibromo-thiazole-5-carbaldehyde (2.5 g, 9.23 mmol) in water (20 ml). The progress of the reaction was monitored by HPLC. More potassium permanganate was added until all of the aldehyde was consumed. The dark suspension was filtered while hot. The filtrate was cooled and acidified with conc. hydrochloric acid to pH=2 to 3. The resulting precipitate was filtered off to afford a white solid as the desired product. The filtrate was lyophilized and methanol was added to dissolve the remaining acid product. The suspension was filtered and the filtrate was concentrated in vacuo. Two crops were combined to give 2,4-dibromo-thiazole-5-carboxylic acid 1.8 g (68%). 1H NMR (300 MHz, DMSO-d6) δ 11.87 (s, 1H).

Provenance & Evidence